Early Human Development, 29 (1992) 251-257 Elsevier Scientific Publishers Ireland Ltd.
251
EHD 01285
Longitudinal measurements of fetal heart rate (FHR) monitoring in second trimester Sato Ikuo, Izumi Akio and Tamada Taro Department
of Obstetrics
and Gynecology,
Jichi
Medical
School,
Tochigi
(Japan)
Summary We investigated the possibility of clinical diagnosis of preterm fetal well-being in the second trimester using the duration of LTVs of less than 4.5 beats/min and characteristic FHR acceleration. Fetuses between 24 and 32 weeks gestation, unlike near-term fetuses are seldom quiet and therefore the prolonged absence of fetal movement may be the best indicator of a sick fetus at these gestational ages. The amplitude and duration of the acceleration of the FHR were also clinically useful diagnostic tools for fetus well-being during the second trimester. Key words: preterm fetus well-being; low amplitude of LTV; acceleration
Introduction It is generally accepted that the monitoring of fetal heart rate (FHR) to determine fetal conditions of term fetus has already been established in clinical practice. This has helped in the development of both the physiologic basis and the appropriate use of the nonstress test in the indication of fetal well-being antenatally [1,2]. Although the nonstress test is widely used in preterm fetuses of 2nd trimester, the criteria of its interpretation have received only preliminary clarification’ [3-51. Therefore, the purpose of our study was to establish the possibility of using FHR monitoring to determine fetal well-being during the 2nd trimester. Patients and Methods Five healthy women were continuously monitored week, from the 20th week of gestation to term. Correspondence
for a period of 2-6 h each
IO: Sato Ikuo, Department of Obstetrics and Gynecology, Jichi Medical School, Tochigi,
Japan. 0378-3782J92/$05.00 0 1992 Elsevier Scientific Publishers Ireland Ltd. Printed and Published in Ireland
----*
,,
“,
,.*‘::‘!‘:3:!*!.l”:y-;::1.
253
The participating women were given an explanation of the study and informed consent was obtained. To monitor the FHR, we used the Toitsu MT 320 and the FHR pattern was analyzed by means of signal processor San-ei 7T18. Sampling time was 500 ms and sampling volume was 30 s. Results Case presentation
This is a FHR-histogram at the 23rd and 30th week of gestation of a 26year old primipara monitored for 2 h. Figure 1 shows the FHR-histogram during 2 h. Each histogram showed fatal heart beats during a period of 12 min. There were 10 histograms, covering a total of 120 min. The FHR baseline values were plotted with a solid line and the variation values with the dotted line at 1Zmin intervals. in this figure, we can see the entire FHR pattern during 2 h. The black blocks showed a low LTV amplitude of less than 4.5 beats/mm. This was a table showing analysis of the FHR variation values of 120 mm, averaged for each 30-s interval. We visually observed LTV amplitudes of 6 beats/mm or less, but according to the Organ calculation formula, 6 beats/mm observed visually correspond to computed analysis values of 4.5 beats/n&. At 23 weeks, the FHR baseline and LTV values showed very little variation, but at the 26th and 30th week the values increased considerably. A low amplitude of less
(min) 18
(%I
16
60 50
40 30
10 7i
20
25 26 26 30 31 32 33 34 35 36 37 38 G;;t;ional
Fig. 3. Duration and percentage of low amplitude of LTV (14.5 beats/min).
254
than 4.5 beats/min was measured in 127 out of 240 sampling, that is, in 53% of the time. However, the LTV’s of less than 4.5 beats/min were of short duration. This is the same patient at 31, 32 and 34 weeks of gestation. A 2-hour FHR-histogram and the LTV value table at 34th week were shown (Fig. 2). Both the FHR baseline and variation value increased, therefore the percentage of low ‘amplitude LTV’s decreased to only 25% of the time, less than at 23 weeks. This is the same patient from the 23rd to the 38th week of gestation, monitored for 2 h. The maximum duration and percentage of low amplitude LTV were shown (Fig. 3). Duration of LTV less than 4.5 beats/min. At 23 to 30 weeks, low amplitude of LTV continued for 5-6 min. At 31-35 weeks, l-2.5 min, after 36 weeks, more than 15 min. Percentage of LTV less than 4.5 beats/min. At 23-25 weeks, low amplitude of LTV accounted for 50% of the time. At 31 weeks, 20%. At 33 weeks, 10%. After 34 weeks, 30-400/o. Amplitude
and duration of FHR acceleration. This is the same patient and amplitude and duration of FHR accelerations were shown (Fig. 4). The X and Y axis represented the amplitude and duration of FHR accelerations, respectively. We see an acceleration of less than 15 beats/min from the 23rd week of gestation, while the duration increased until the 28th week. After 30th week, as you can see, both the amplitude and the duration of acceleration increased. This is the FHR accelerations of the same patient at 31-34 week (Fig. 5). We see here that while amplitude of the accelerations increased, the duration decreased.
5i-TFTF &PL
liUI,E
(26W
(25W
WWI
J
T1& kl,lPL
I TIJIJE
0
N= 18 n
T
I T 0 l‘lT lil-lPL
I TiiDE
AMPLITUDE
Fig. 4. Amplitude and duration of acceleration (W.Y. number I).
CIMPL I TUDE
(33W)
(34W ,J
_
..
~M?L*Imi
,Eyl’
Fig. 5. Amplitude and duration of acceleration (W.Y. number 2).
(mid 19-
15.
60 10.
50 40
30 5. 20 10
7 i
10 19 20 21 22 23 24 25 26 27 20 29 30 31 32 33 34 35 36 31
Fig. 6. Mean duration and percentage of low amplitude of LTV ( ~4.5
38 39 40
beatshin).
256
Mean duration and percentage of LTV/S of less than 4.5 beats/min in 5 healthy pregnant women
The bar graph showed the duration of LTV’s of less than 4.5 beats/min during the gestation period indicated (Fig. 6). At 18-27 weeks, low amplitude of LTV continued 5- 10 min. At 28-34 weeks, 4-7 min. After 36 weeks, more than 15 min. The dotted line showed the percentage of LTV’s of less than 4.5 beatsJmin during 120 min of monitoring. At 18-27 weeks, low amplitude of LTV accounted for 45-60%. At 28 to 34 weeks, 35-45%. After 35 weeks, 45-60%. Characteristic FHR acceleration pattern in 5 healthy pregnant women.
We can see an acceleration of more than 10 beatsJmin from 23rd or 24th week of gestation. Until the 30th week, there is mostly an increase in amplitude of acceleration and a reduction in the duration of the acceleration. Discussion and Conclusions Longterm simultaneous recording of FHR in the 3rd trimester has established that the existence of cycles of rest and activity in the human fetus [ 1,2]. This concept has led to the physiologic basis for the appropriate clinical use of fetal biophysical measurements for the identification of fetal well-being antenatally. Although the FHR monitoring was used in preterm fetus during the 2nd trimester, the criteria of fetal well-being has not been established in clinical practice [3-51. Therefore, we investigated the possibility of clinical diagnosis of preterm fetus in the 2nd trimester using duration of LTV’s of less than 4.5 beats/min and characteristic FHR acceleration. As a result, it was found that the duration of LTV (24.5 beats/min) was within 10 min until 27 weeks’ gestation and between 28 and 32 weeks’ gestation duration of the LTV (~4.5 beats/min) was within 7 min. And then, it was also found that the acceleration of more than 10 beats/min was observed from the 24th week of gestation, until the 30th week, there was mostly an increase in duration of acceleration and after 30th week, there was an increase in amplitude or acceleration and a reduction in the duration of the acceleration. This suggests that periodicities in fetal body movements are probably not clearly established in younger fetuses until 30-32 weeks’ gestation. This is clinically important because, unlike near-term fetuses, fetuses between 24 and 32 weeks gestation are seldom quiet and therefore the prolonged absence of fetal movement may be best indicator of a sick fetus at these gestational ages. In conclusion, we suggested that the findings of the duration of LTV’s of less than 4.5 beats/min and the amplitude and duration of the acceleration of the FHR, were clinically useful diagnostic tools for monitoring fatal well-being during the 2nd trimester of pregnancy. Refercences 1
Patrick, J., Campbell, K., Carmichael and Probert, gross fetal body movements on the daily pattern Gynecol., 144, 533.
C., (1982): Influence of fetal heart rate
of maternal near term.
heart rate and Am. J. Obstet.
257 2 3 4 5
Dawes, G.S, Houghton, C.R.S., Redman, C.W.G. and Visser, G.H.A. (1982): Patterns of normal human fetal heart rate. Br. J. Obstet. Gynaecol., 88, 270. Natale, R., Nasello, C. and Turliuk, R. (1984): The relationship between movements and accelerations in fetal heart rate at twenty-four to thirty-two weeks’ gestation. Am. J. Obstet. Gynecol., 148, 591. Natale, R., Nasello-Paterson, C. and Turliuk, R. (1985): Longitudinal measurements of fetal breathing, body movements, heart rate, and heart rate accelerations and deceleration at 24 to 32 weeks of gestation. Am. J. Obstet. Gynecol., 151, 256. Arduini, D., Rizzo, G., Giorlandino, C., Valensise, H., Dellacqua, S. and Romanini, C. (1986): The development of fetal behavioural states: a longitudinal study. Prenat. Diagn., 6, 117.
251
EHD 01285
Longitudinal measurements of fetal heart rate (FHR) monitoring in second trimester Sato Ikuo, Izumi Akio and Tamada Taro Department
of Obstetrics
and Gynecology,
Jichi
Medical
School,
Tochigi
(Japan)
Summary We investigated the possibility of clinical diagnosis of preterm fetal well-being in the second trimester using the duration of LTVs of less than 4.5 beats/min and characteristic FHR acceleration. Fetuses between 24 and 32 weeks gestation, unlike near-term fetuses are seldom quiet and therefore the prolonged absence of fetal movement may be the best indicator of a sick fetus at these gestational ages. The amplitude and duration of the acceleration of the FHR were also clinically useful diagnostic tools for fetus well-being during the second trimester. Key words: preterm fetus well-being; low amplitude of LTV; acceleration
Introduction It is generally accepted that the monitoring of fetal heart rate (FHR) to determine fetal conditions of term fetus has already been established in clinical practice. This has helped in the development of both the physiologic basis and the appropriate use of the nonstress test in the indication of fetal well-being antenatally [1,2]. Although the nonstress test is widely used in preterm fetuses of 2nd trimester, the criteria of its interpretation have received only preliminary clarification’ [3-51. Therefore, the purpose of our study was to establish the possibility of using FHR monitoring to determine fetal well-being during the 2nd trimester. Patients and Methods Five healthy women were continuously monitored week, from the 20th week of gestation to term. Correspondence
for a period of 2-6 h each
IO: Sato Ikuo, Department of Obstetrics and Gynecology, Jichi Medical School, Tochigi,
Japan. 0378-3782J92/$05.00 0 1992 Elsevier Scientific Publishers Ireland Ltd. Printed and Published in Ireland
----*
,,
“,
,.*‘::‘!‘:3:!*!.l”:y-;::1.
253
The participating women were given an explanation of the study and informed consent was obtained. To monitor the FHR, we used the Toitsu MT 320 and the FHR pattern was analyzed by means of signal processor San-ei 7T18. Sampling time was 500 ms and sampling volume was 30 s. Results Case presentation
This is a FHR-histogram at the 23rd and 30th week of gestation of a 26year old primipara monitored for 2 h. Figure 1 shows the FHR-histogram during 2 h. Each histogram showed fatal heart beats during a period of 12 min. There were 10 histograms, covering a total of 120 min. The FHR baseline values were plotted with a solid line and the variation values with the dotted line at 1Zmin intervals. in this figure, we can see the entire FHR pattern during 2 h. The black blocks showed a low LTV amplitude of less than 4.5 beats/mm. This was a table showing analysis of the FHR variation values of 120 mm, averaged for each 30-s interval. We visually observed LTV amplitudes of 6 beats/mm or less, but according to the Organ calculation formula, 6 beats/mm observed visually correspond to computed analysis values of 4.5 beats/n&. At 23 weeks, the FHR baseline and LTV values showed very little variation, but at the 26th and 30th week the values increased considerably. A low amplitude of less
(min) 18
(%I
16
60 50
40 30
10 7i
20
25 26 26 30 31 32 33 34 35 36 37 38 G;;t;ional
Fig. 3. Duration and percentage of low amplitude of LTV (14.5 beats/min).
254
than 4.5 beats/min was measured in 127 out of 240 sampling, that is, in 53% of the time. However, the LTV’s of less than 4.5 beats/min were of short duration. This is the same patient at 31, 32 and 34 weeks of gestation. A 2-hour FHR-histogram and the LTV value table at 34th week were shown (Fig. 2). Both the FHR baseline and variation value increased, therefore the percentage of low ‘amplitude LTV’s decreased to only 25% of the time, less than at 23 weeks. This is the same patient from the 23rd to the 38th week of gestation, monitored for 2 h. The maximum duration and percentage of low amplitude LTV were shown (Fig. 3). Duration of LTV less than 4.5 beats/min. At 23 to 30 weeks, low amplitude of LTV continued for 5-6 min. At 31-35 weeks, l-2.5 min, after 36 weeks, more than 15 min. Percentage of LTV less than 4.5 beats/min. At 23-25 weeks, low amplitude of LTV accounted for 50% of the time. At 31 weeks, 20%. At 33 weeks, 10%. After 34 weeks, 30-400/o. Amplitude
and duration of FHR acceleration. This is the same patient and amplitude and duration of FHR accelerations were shown (Fig. 4). The X and Y axis represented the amplitude and duration of FHR accelerations, respectively. We see an acceleration of less than 15 beats/min from the 23rd week of gestation, while the duration increased until the 28th week. After 30th week, as you can see, both the amplitude and the duration of acceleration increased. This is the FHR accelerations of the same patient at 31-34 week (Fig. 5). We see here that while amplitude of the accelerations increased, the duration decreased.
5i-TFTF &PL
liUI,E
(26W
(25W
WWI
J
T1& kl,lPL
I TIJIJE
0
N= 18 n
T
I T 0 l‘lT lil-lPL
I TiiDE
AMPLITUDE
Fig. 4. Amplitude and duration of acceleration (W.Y. number I).
CIMPL I TUDE
(33W)
(34W ,J
_
..
~M?L*Imi
,Eyl’
Fig. 5. Amplitude and duration of acceleration (W.Y. number 2).
(mid 19-
15.
60 10.
50 40
30 5. 20 10
7 i
10 19 20 21 22 23 24 25 26 27 20 29 30 31 32 33 34 35 36 31
Fig. 6. Mean duration and percentage of low amplitude of LTV ( ~4.5
38 39 40
beatshin).
256
Mean duration and percentage of LTV/S of less than 4.5 beats/min in 5 healthy pregnant women
The bar graph showed the duration of LTV’s of less than 4.5 beats/min during the gestation period indicated (Fig. 6). At 18-27 weeks, low amplitude of LTV continued 5- 10 min. At 28-34 weeks, 4-7 min. After 36 weeks, more than 15 min. The dotted line showed the percentage of LTV’s of less than 4.5 beatsJmin during 120 min of monitoring. At 18-27 weeks, low amplitude of LTV accounted for 45-60%. At 28 to 34 weeks, 35-45%. After 35 weeks, 45-60%. Characteristic FHR acceleration pattern in 5 healthy pregnant women.
We can see an acceleration of more than 10 beatsJmin from 23rd or 24th week of gestation. Until the 30th week, there is mostly an increase in amplitude of acceleration and a reduction in the duration of the acceleration. Discussion and Conclusions Longterm simultaneous recording of FHR in the 3rd trimester has established that the existence of cycles of rest and activity in the human fetus [ 1,2]. This concept has led to the physiologic basis for the appropriate clinical use of fetal biophysical measurements for the identification of fetal well-being antenatally. Although the FHR monitoring was used in preterm fetus during the 2nd trimester, the criteria of fetal well-being has not been established in clinical practice [3-51. Therefore, we investigated the possibility of clinical diagnosis of preterm fetus in the 2nd trimester using duration of LTV’s of less than 4.5 beats/min and characteristic FHR acceleration. As a result, it was found that the duration of LTV (24.5 beats/min) was within 10 min until 27 weeks’ gestation and between 28 and 32 weeks’ gestation duration of the LTV (~4.5 beats/min) was within 7 min. And then, it was also found that the acceleration of more than 10 beats/min was observed from the 24th week of gestation, until the 30th week, there was mostly an increase in duration of acceleration and after 30th week, there was an increase in amplitude or acceleration and a reduction in the duration of the acceleration. This suggests that periodicities in fetal body movements are probably not clearly established in younger fetuses until 30-32 weeks’ gestation. This is clinically important because, unlike near-term fetuses, fetuses between 24 and 32 weeks gestation are seldom quiet and therefore the prolonged absence of fetal movement may be best indicator of a sick fetus at these gestational ages. In conclusion, we suggested that the findings of the duration of LTV’s of less than 4.5 beats/min and the amplitude and duration of the acceleration of the FHR, were clinically useful diagnostic tools for monitoring fatal well-being during the 2nd trimester of pregnancy. Refercences 1
Patrick, J., Campbell, K., Carmichael and Probert, gross fetal body movements on the daily pattern Gynecol., 144, 533.
C., (1982): Influence of fetal heart rate
of maternal near term.
heart rate and Am. J. Obstet.
257 2 3 4 5
Dawes, G.S, Houghton, C.R.S., Redman, C.W.G. and Visser, G.H.A. (1982): Patterns of normal human fetal heart rate. Br. J. Obstet. Gynaecol., 88, 270. Natale, R., Nasello, C. and Turliuk, R. (1984): The relationship between movements and accelerations in fetal heart rate at twenty-four to thirty-two weeks’ gestation. Am. J. Obstet. Gynecol., 148, 591. Natale, R., Nasello-Paterson, C. and Turliuk, R. (1985): Longitudinal measurements of fetal breathing, body movements, heart rate, and heart rate accelerations and deceleration at 24 to 32 weeks of gestation. Am. J. Obstet. Gynecol., 151, 256. Arduini, D., Rizzo, G., Giorlandino, C., Valensise, H., Dellacqua, S. and Romanini, C. (1986): The development of fetal behavioural states: a longitudinal study. Prenat. Diagn., 6, 117.
